Timing mechanism for camera focal plane shutter



June 23, 1959 w. STEIN ETAL TIMING MECHANISM FOR CAMERA FOCAL PLANESHUTTER 4 Sheets-Sheet 1 Original Filed Aug. 28, 1951 June 23, 1959 w.STEIN ETAL 2,891,455

TIMING MECHANISM FOR CAMERA FOCAL PLANE SHUTTER original Filed Aug. 28,19'51 1 4 sheets-sheet '2 2W/M. INVENTOR;

June 23, 1959 w. STEIN l-:TAL 2,891,455 v TIMING MECHANISM FOR CAMERAFOCAL PLANE SHUTTER Original Filed Aug. 28, 1951 4 Sheets-Sheet 5 `t @a5 30 y 22 31 19a /318 25" 'um "41521, .1.9 l'yzW//f fiimm 9 12e fln" W17li 20a @will i gl Il I 13 2'0"!3@ .11a l 201, 16

I ,ll //"3.13 33 v wTmTL''G-"J" 11b 251 Q/WIN w g "I 'l 12a 27 0a 23 um)Q5/13a ya '1o 16 INVENTORSv June 23, 1959 W 'sTElN ETAL 2,891,455

TIMING MECHANISM FOR CAMERA FOCAL PLANE SHUTTEB.

Original Filed Aug. 28. 1951 4 Sheets-Sheet 4 n 24 A 25h I c H /Jla 27nmlmnlwidlllll Fg@ a 77W 4%: INVENToRs aar Wujw? Y BY United StatesPatent C) TIMING MECHANISM FOR CAlVIERA FOCAL PLANE SHUTTER WilhelmStein and Hugo Wehrenfennig, Wetzlar (Lahn), Germany Continuation ofapplication Serial No. 244,004, August 28, 1951. This applicationDecember 28, 1955, Serial No. 555,806

Claims. (Cl. 95-57) This application is a continuation of ourapplication Serial Number 244,004, led August 28, 1951, and nowabandoned, for improvements in timing mechanisms for camera focal planeshutters in which the shutter curtains are released, one after theother, without mechanical limitation of the size of the exposure openingor slit bctween the curtains. The first curtain is released by manualoperation of the shutter or camera release. The release of the secondcurtain is controlled both by the movements of the first curtain andalso by a cam mechanism which in turn is governed in its operations bythe settings of the main speed dial knob or timing knob of the camera.

The invention disclosed in this application is an improvement upon and adevelopment of the camera shutter mechanism disclosed in the U.S. PatentNo. 2,122,671, dated July 5, 1938, in which the release of the secondcurtain is dependent upon the operations of many elements interveningbetween the release of the first curtain and that of the second curtain.

With such known timing mechanisms it is diicult to control the releasemovements when high speeds or short exposures are desired. lt is alsodiicult to arrange the moments lof the curtain releases for any desiredexposure, particularly with respect to the provision of a timingmechanism which is adapted for connection with an exposure meter.

The object of this invention is therefore to provide a curtain shuttertiming mechanism in which a certain improved cam mechanism is providedto insure a definite determination of the timing of the curtain releasesby relatively long movements of the timing elements between thereleases. Another object is to provide a timing mechanism in which theoperation or setting of the timing knob will no longer necessarily bestepwise in accordance with the time markings on the camera, butexposures of any lengths may be obtained. Another object is to provide atiming mechanism wherein a single timing knob will suffice for adjustingthe time controlling elements to operate for any desired exposure,including for example, exposures from one second to 1/1000 of a second.Other features and objects of the invention will be best understood fromthe following specification and the accompanying drawings in which:

Fig. 1 is a detail view in elevation of the camera shutter mechanismwith parts broken away and parts removed. The view is takensubstantially in the direction of the arrow 1 in Fig. 2.

Fig. 2 is a top plan view of the timing mechanism embodying theinvention showing the parts adjusted for a high speed or short exposure,parts being in section.

Fig. 3 is a sectional view through the timing knob and the improved cammechanism with parts removed and parts broken away. Some elements of themech anism are shown displaced for the sake of clearness.

Fig. 4 is a side view of the release and blocking members with parts insection and parts removed, the view being taken substantially on theline 4 4 of Fig. 2.

2,891,455 Patented June 23, 1959 ICC Fig. 5 is a plan view showing themechanism adjusted for a short exposure different from the shortexposure position shown in Fig. 2.

Fig. 6 is a similar View showing the parts adjusted for a longerexposure.

Fig. 7 shows the parts adjusted for a still longer exposure.

Fig. 8 shows the parts adjusted for time exposures.

The timing mechanism disclosed herein is arranged .for exposuresgoverned by improved cam means, including certain brake means, which areset for the different exposures. Two differently adjusted positions ofthe parts for two examples of short exposures are shown in Figs. 2 and5. For longer exposures the release of the second curtain is delayed bya certain escapement brake mechanism and the positions of the cams forsuch longer exposures are shown in Fig. 6 as an example. A still furtherdelay in the release of the second curtain is obtained by setting thetiming cams in such positions that not only the escapement brake meansbut also a braking anchor which otherwise is included in the brake meansis operated to cause a longer delay in the release of the secondcurtain, and the corresponding positions of the cams are shown in Fig.7.

ln these settings of the timing mechanism the operator actuates thecamera release manually only once and the correct time exposure is thencontrolled by the timing mechanism itself. Fig. 8 shows the positions ofthe timing earns for the so-called B-time exposures in which the shutteris held open by the operator for whatever time exposure he may desire.

Fig. l illustrates generally the known parts of a curtain shutter whichincludes the two curtains 1 and 2 which are carried on bands wound uponsheaves 4 mounted on a shaft 3. T he curtains carrying drum 5 is coupledto the shaft 3. The timing mechanism is indicated at 6. The main speeddial or timing knob is marked 7. The shutter release is at 8. When therelease is depressed by the operator the gear 4a is disengaged from thegear 3a on the shaft 3 and the clutch means at 4b are disengaged fromthe winding up mechanism which winds up the bands and film transportingsprings. The first curtain is released by the depression of the releaseS and the curtain is then drawn across the camera by its transportingspring indicated at la, Fig. l, After a desired time interval the secondcurtain is released and follows the rst curtain a certaindistance-exposure opening-therefrom.

Alongside the drum 5 there is supported an axially movable shaft i4, thetop of which is broken away in Fig. l. The shaft 14' rests upon thespring 8a. When the release 3 is depressed, the spring 8a is moved downand the shaft 14 also moves down. rihe first curtain then runs off toform the leading edge of the exposure opening between the curtains. Thesecond curtain is prevented from moving until it is released by aseparate release mechanism hereinafter described. Thereafter the twocurtains move together across the camera with an exposure openingbetween them which depends upon the setting of the timing knob.

Referring now to Fig. 3 it will be seen that the band sheaves 4 arepinned to the shaft 3 which also has pinned thereto a release disk whichis a part of the improved cam mechanism according to this invention. Therelease disk 9 has a release nose 9a. The drum 5 is freely rotatable onthe shaft 3 and is coupled to a stop disk 11 by a pin 10 which projectsupward through an opening 4c into an open slot in the disk 11. Thelatter is also freely rotatable on the shaft 3. The upper end of theshaft 3 is conveniently supported in a cam shaft 12 secured to thetiming knob 7.

The stop disk 11 has two stop fingers 11a and 11b.

Fig. 2 shows the finger 11a below the shaft 12 and the other finger 11babove the shaft 12. The stop finger 11a is adapted to engage a stoptooth 13a on the free end of a stop lever 13 which is pivoted on theshaft 14 and moves vertically therewith. A spring 15 engages aneccentric knob 16 rotatably carried on the stop lever 13 and the springacts to press the stop tooth 13a against a fixed stop 17 arranged in thecamera.

Inasmuch as the stop disk 11 is coupled to the curtain drum 5 by the pin10, Fig. 3, it follows that so long 'as the stop finger 11a on stop disk11 engages the stop tooth 13a, the second curtain can not move. Notuntil vthe stop lever 13 is swung outward about the shaft 14 ltodisengage the stop tooth 13a from the stop finger 11a so as to leave thestop disk free to rotate about the shaft 3 is the second curtain drum 5released for rotation. The stop lever 13 participates in the downwardmovement of the shaft 14 when the shutter is released so that the stoptooth 13a is moved down to engage the stop finger 11a to preventimmediate release of the second curtain.

The cam shaft 12, secured to the timing knob 7, carries three integraltiming cams. The cam 12e is the uppermost cam, the cam 12a is the middlecam and the cam 12b is the lowermost cam. The three cams rotate with thetiming knob 7, Fig. 3.

The first, uppermost, cam 12e controls the positions of a three-armedlever 25 pivoted at 26, Fig. 2. One arm 25a engages the cam. A secondarm 25b controls the movement of a pivoted anchor 28, which is part ofthe escapement brake mechanism, by engaging with an anchor lug 27projecting upwardly through an opening 27a in the pivoted escapementsupport 22. The third arm 25C moves within the range of a cam disk 29 onthe upper end of a shaft 29 which is rotated by operation of the shutterwinding up means, Fig. 1.

The second, middle, timing cam 12a controls the positioning of atwo-armed lever 19 pivoted at 13, Fig. 2. One arm 19a of the leverengages the cam 12a under the pressure of a spring 21. The other arm 19his a two-layer arm, Fig. 4, which supports a pivot 20d between the twolayers of the lever arm. A releasing lever 20 is pivoted on the pivot20d and controls the disengagement of the stop tooth 13a from the stopfinger 11a in that said releasing lever 20 is kept in sliding contactwith the said eccentric knob 16 on the stop lever 13 by a spring 20cacting upon the two layer arm of the lever 19.

The third, lowermost, timing cam 12b controls the position of theaforesaid escapement brake support 22 which is in the form of an armpivoted at 23, Fig. 2, and extends alongside the cam mechanism. A spring22a keeps a finger 24 at the supports free end in contact with the thirdlowermost timing cam 12b. The support at its free end also carries apivot 30 for a swingable toothed segment 31 which has a hook nose 31a. Aspring 30a keeps the segment in mesh with the escapement gearing unit 32on the pivoted support 22 whereby to increase the running downresistance of the gears and whereby to move the gears 32 back intooriginal position after the delayed release of the second curtain. Thehook nose 31a is adapted to be moved into the path of movement gf thesecond stop finger 11b of the stop disk 11, see

The toothed segment 31 meshes with the gears 32 under pressure of thespring 30a as shown whereby to cause rotation of the anchor gear 33,Fig. 2, which is located opposite the aforesaid braking anchor 28. Theanchor is pivoted at 28a on a swingable arm 34 pivoted at 34a on theescapement support 22. A spring 35 keeps the anchor lug 27 in engagementwith the arm 25b of the three-armed lever 25. It follows therefor thatthe lowermost timing cam 12b controls the swinging movement of theescapement support 22 about the pivot 23.

When the shutter is rewound after an exposure, the stop disk 11 which iscoupled to the second curtain via the upstanding pin 10 is rotatedcounterclockwise with the second curtain so that the stop finger 11a isbrought in front of the stop tooth 13a to block immediate release of thesecond curtain.

The operations are as follows: As shown in Fig. 5, when the timing knob7 is set for a short exposure, rotation of the knob and the cam shaft 12positions all the cams in the cam mechanism whereby the lowermost cam12b moves the braking member support 22 and the toothed segment 31outward as shown and the segment hook nose 31a is no longer within therange of movement of the stop disk 11. The uppermost timing cam 12e isso positioned that its high point contacts the arm 25a of thethree-armed lever 25, so that the second arm 25h will disengage theanchor 28 from the gear 33.

The reason for disengaging the anchor although the escapement support 22as such is moved into inactive position by the cam 12b is to relieve thesegment spring 22a from any extra pressure and in order to insure anunobstructed return to active position of the escapement support 22 andits associated parts for all exposures after the shutter has beenreleased. The anchor 28 is thus operated in dependence upon the windingup mechanism of the shutter in that the arm 25e` of the anchor lever 25moves within the range of movement of the cam disk 29 carried by thetoothed shaft 29a, Fig. 1, and whereby, when the shutter is rewound, theanchor is disengaged from the anchor gear 33.

The second, middle, timing cam 12a is so positioned that the two-armedlever 19 has been moved counterclockwise to cause a sliding movement ofthe release lever 20 along and, to the right, upon the eccentric knob 16whereby said lever 20 has been spaced a definite distance from the nose9a of the release disk 9 which is pinned to the shaft 3. The two-armedlever 19 moves the release lever 20 by means of the lever arms 19h andthe pivot 20d, Fig. 4. It will be noted that at this time the entireescapement mechanism is inactive and that the p0- sitioning of thetiming cam 12a determines, i.e. varies the position of the releasinglever 20 with relation to the nose 9a of the releasing disk 9.

When the shutter is released by depressing the release 8, the shaft 14with the stop lever 13 thereon is moved down so that the stop tooth 13ais brought down lever with the stop disk 11, Fig. 3. The first curtainis now released and runs off. The second curtain does not move at thistime because the stop tooth 13a of the stop lever 13 lies in the path ofmovement of the stop finger 11a of the stop disk 11 which is coupledwith the curtain drum 5. Movement of the stop disk 11 and of the secondcurtain is therefore prevented. The pin 10 which couples the stop disk11 to the curtain drum 5 is positioned by the Winding up of the shutter.

However, the release disk 9 with the release nose 9a rotates with thefirst curtain and after the adjusted time interval, the nose 9a strikesthe release curve 20a of the release lever 20. The latter is providedwith another curved surface 2Gb which slides along and upon theeccentric knob 16 on the stop lever 13. The latter is therefore swungoutward so that the stop tooth 13a becomes disengaged from the stopfinger 11a. The blocking action of the two engaged members 13a and 11ano longer exists and the second curtain now runs off to follow the firstcurtain with an exposure opening between the curtains according to thesetting of the timing knob 7. The second curtain is moved across thecamera by a spring positioned parallel with the spring 1a. The timeinterval between the movements of the two curtains therefore dependsupon the length of time it takes for the release nose 9a to reach andstrike the release curve 20a. Until this happens, the second curtain cannot move. When the shutter is rewound, the parts return to their initialpositions. It should be noted that the power supplied to the releasedisk 9 and to the release nose 9a for striking the release lever 20cornes solely from the transporting spring 1a which moves the firstcurtain across the camera. Thus additional springs are not required forthis purpose.

When the timing knob is set for longer, intermediate, exposures, thecams are positioned as shown in Fig. 6. The segment nose 31a is broughtwithin the range of the stop finger 11b. The anchor remains disengagedfrom the anchor gear 33 because of the position of the threearmed lever25 on the cam 12C. The middle cam 12a is so positioned that the releasedcurve of the lever 20 is again spaced a definite distance from therelease disk nose 9a.

Fig. 6 therefore illustrates the parts in the positions in which theexposure operation includes the participation of the escapement brakemechanism carried by the pivoted support 22 and whereby the release ofthe second curtain is delayed. In this figure it will be observed thatthe stop tooth 13a no longer engages the stop finger 11a andconsequently there is no longer any blocking action existing betweenthese two members. At the same time however, the other stop finger 11bhas run against the hook nose 31a on the toothed segment 31. The stopdisk 11 is operatively connected with the second curtain as shown at and10, Fig. 3. There is a spring for each curtain to draw it across thecamera. The spring for the second curtain is not shown herein, but it ispositioned parallel with the spring lla described above. The positionsand operations of the two springs and the two curtains are fullydisclosed in the patent hereinbefore referred to.

The drawing power of the second curtain spring acts upon the hook nose31a and tends to move it in a counterclockwise direction about the pivot30. The spring 30a is therefore tensioned and the gears 32 and 33 arecaused to rotate. The parts are so designed and proportioned that theturning moment of the toothed segment 31 causes a quick rotation of thegear 33. The frictional resistance of the movements of these partstoether with the resistance of the spring 30a result in a relativelyslow movement of the hook nose 31a until the stop finger 11b slides offthe hook nose 31a and permits the release of the second curtain. Theresistance of the rotating gears 32 and 33 serve to slow down thereleasing movement of the second curtain.

In operation, the first curtain is run off as explained above and thebreaking up of the blocking action of the two members 13a and 11a islikewise as aforesaid. After the disengagement of these two members, thestop disk 11 with the stop finger 11b will be held immovable by the`hook nose 31a until the segment 31 under the influence of the spring,as at 1a, which transports the second curtain across the camera, andagainst the resistance of the running gears 32 as well as against theforce of the segment spring 30a has been swung counterclockwise so farabout its pivot 30 that the segment hook nose 31a has been disengagedfrom the stop finger 11b.

Now the second curtain runs off to form the rear edge of the exposureopening between the curtains, the width of the opening being determinedby the adjusted distance between the release nose 9a and the releasecurve 2Gb on the lever 20 as well as by the depth of the contact betweenthe hook nose 31a and the stop iinger 11b. With the parts thuspositioned the anchor 28 of the escapement mechanism is automaticallydisengaged from the operating parts of the timing mechanism. In thiscase, therefore, the time interval between the releases of the twocurtains depends not only upon the spacing between 9a and 20a, but alsoupon the length of time it takes to disengage the segment hook nose 31afrom the stop finger of 11b. Fig. 5 shows the parts in the positions foran exposure without participation of the escapement mechanism and beforethe release of the first curtain. Fig. 6 shows the parts in thepositions when a longer exposure is desired and the second curtain isdelayed in its release.

6 This figure shows the positions of the parts just before the secondcurtain runs off.

Fig. 7 illustrates the positions of the parts when the timing knob isset for still longer exposures. In this case the uppermost cam 12e is sopositioned that the arm 25a of the lever 25 is on the low part of thecam as shown, and no longer prevents the anchor 28 from engaging thegear 33 under the force of the spring 35. The segment hook nose 31a nowengages the stop nger 11b.

The release of the shutter and the movements of the shutter curtainstake place as explained above, but inasmuch as the anchor 28 delaysrotation of the gears 32, the toothed segment hook nose 31a will remainlonger in the path of the stop linger 11b until the segment has beenswung so far about its pivot 30 that the nose 31a becomes disengagedfrom the stop finger and the release disk 11 therefore is free to rotateand the second curtain is released. Thus, the disengagement of the nose31a from the stop nger 11b has been delayed and the exposure is longer.

Thus, by the setting of the timing knob and the timing cams as shown inFigs. 2, 5, 6 and 7, and in accordance with markings on the camera forshort or shorter exposures, the exposures are made by depressing therelease of the camera and the mechanism then functions automatically.

Fig. 8 shows the parts adjusted for time exposures. The middle cam 12ais now so positioned that the lever arm 19u rests upon the low camportion 12d whereby the release lever 2@ is moved entirely beyond therange of movement of the release cam disk nose 9a of the disk 9. Theescapement brake mechanism is inactive as evidenced by the position ofthe brake nger nose 24 on the high part of the cam 12b.

When the shutter is released7 the second curtain is prevented frommoving because of the engagement of the blocking members 11a and 13a asshown. The second curtain moves to complete the exposure when theoperator takes his nger off the shutter release 8 whereby the stop lever13 with the stop tooth 13a, moving upwardly with the shaft 14, iselevated by the spring Sa and thereby raised above the level of the stopdisk 11, Fig. l. When the shutter is rewound, the cam 29 on the shaft29a, Fig. 2, engages the arm 25C of the lever 25 so as to move the otherarm 25b to cause the anchor to be disengaged from the gear 33 whereby toinsure that the gears 32 and the segment 31 easily and quickly return tostarting positions. it also prevents wear on the gears and eliminatesnoise.

The movements of the release lever 20 is tangential with respect to therotating movement of the release cam nose 9a on the release disk 9,thereby providing for a relative large movement of the parts betweenshort exposures or for short exposures. The formation of the releaselever 2t) with the curve 20a for contact with the release disk 9together with the sliding curved surface 2%, Figs. 5 and 8, whichengages the eccentric knob 16 makes it possible to mark the timing knobor the camera with any desired time intervals.

The disclosed arrangement also makes it possible to attach an exposuremeter, not shown, directly to the timing knob having in mind thecharacteristic features of such a meter. The use of curved camsregulating the positions of the time controlling elements enables theoperator to set the timing mechanism for selected exposures without thenecessity of setting the timing knob with relation to a definiteexposure scale. The timing knob 7, Fig. 3, is provided with a circulargroove 7a which moves over a fixed stop 7b whereby to limit the rotarymovement of the knob. This is a practical advantage when the knob isconnected with an exposure meter.

The knob 16 is eccentrically mounted -upon the stop lever 13 so that themovement of the release lever 20 along and against the knob will causeautomatic adjusty ment of the lever 20 with relation to the release disknose 9a. The weight of the two moving bodies of the two levers 20 and 13will have a restraining effect upon the movement of the `release disk 9and therefore also upon the movement ofthe first curtain so that thespeed thereof will be more evenly proportional with relation to thespeed of the second curtain.

When the release 8 is depressed, the shaft 3 is free to rotate so thatthe first curtain can run olf across the camera by the usual curtaintransporting spring, Fig. l. rIlhe second curtain can not then run offbecause the stop lever 13 has -been moved down to prevent rotation ofthe stop disk 11 which is coupled to the curtain drum 5. In Fig. 8 thelever 13 prevents rotation of the stop disk 11 (run off of the secondcurtain) until the operator releases his pressure upon the release 8after the time exposure. In Fig. 7 the braking action of the anchor isbrought into play so that a delay occurs before the release cam nose 9acan reach and engage the release curve 20a on the lever 20. In Fig. 6the additionally delaying action of the anchor is removed and a shorterexposure provided for. In Fig. the operation of the timing mechanismprovides for short exposures in that the lapse of time between the runoffs of the two curtains is equal only to the time it takes for the earnnose 9a to reach the curve 20b, all other interfering factors beinginactive.

The invention herein disclosed is superior in operation in that itprovides a direct action releasing blow by the releasing cam nose 9aupon the releasing lever 20, the releasing power or force being supplieddirectly by the first curtain transporting spring without anyintervening elements, and without any variation in the force or tensionof the actuating spring. The releasing lever never contacts thereleasing disk 9 until struck by the releasing nose 9a. The releasinglever need not therefore have any particular formation except that itscurved form and its sliding contact with the eccentric knob 16 providesmeans for an infinite fine adjustment.

The operation of the mechanism is of course wholly automatic in responseto the setting of the timing knob and timing means carried by the knob.The several cams, levers and associated parts are conveniently mountedbelow the knob 7 and generally indicated by the reference numeral 6. Theinvention herein disclosed is not necessarily limited to the precisedetails of construction described and illustrated and we claim all suchchanges and modifications as come within the principle of the inventionand the scope of the appended claims.

We claim:

l. A camera shutter mechanism comprising a first and a second normallyclosed shutter curtain successively released to provide an exposureopening between them, a timing mechanism controlling the time intervalbetween successive releases of said curtains comprising a shaftrotatable with the release of the first curtain, a release disk pinnedon said shaft to rotate therewith, a stop disk freely rotatable aboutsaid shaft and operatively connected with the second curtain, avertically movable and swingably supported stop lever normallydisengaged from said stop disk, means for moving said stop lever toengage said stop disk to prevent rotative movement thereof and releaseof the second curtain simultaneous with the release of the firstcurtain, a release lever, a two-armed lever pivotally supporting saidrelease lever and provided with a first cam nose, means on said stoplever operatively engaging the release lever to maintain the latter inthe path of rotation of said release disk to be engaged thereby, amiddle timing cam engaged by said first cam nose, a gear unit adapted todelay release of the second curtain, a pivoted arm supporting said gearunit and provided with a second cam nose, a gear unit cam engaged bysaid second cam nose, a timing shaft integral with the said two cams, aknob integral with said timing shaft for rotating the latter and thesaid two cams to move the said gear unit supporting arm and gear unitinto an inactive position in said timing mechanism and to move saidrelease lever in slidable engagement with said maintaining means into apredetermined spaced relation to said releasing disk to be engaged bythe latter, as said disk is rotated upon release of the first curtain,to cause disengagement of said stop lever from said stop disk whereby torelease the second curtain, said gear unit for delaying release of thesecond curtain including a toothed segment lever pivoted on said unitsupporting arm, said freely rotating stop disk having a stop fingerprojecting therefrom, said segment lever having a stop noseautomatically positioned in the path of rotation of said stop diskfinger when said gear unit cam nose is placed in delayed exposureposition by rotation of said timing shaft and gear unit cam, a springengaging said toothed segment lever to move the same to increase therunning down resistance of the gearing and to restore said toothedsegment to original position after the delayed start of the secondcurtain, a second spring for keeping the said stop nose in the path ofrotation of said stop disk finger and spring means connected with thesecond curtain for transporting the same for moving said segment noseout of the path of rotation of said stop disk finger whereby to releasethe second curtain.

2. A timing mechanism as claimed in claim l including means forincreasing the motion resistance in said gear unit comprising an anchorpivoted on said unit supporting arm, a spring on said arm urging saidanchor into engagement with the gears in the unit to increase the motionresistance therein, a pivotally supporting anchor lever engaging saidanchor to normally disengage the anchor from the unit, an anchor camintegral with said gear unit cam and with said timing shaft, an anchornose on said anchor lever engaging said anchor cam whereby when saidtiming shaft and anchor are adjusted for an exposure requiring inclusiveoperation of said `gear unit, said anchor lever is disengaged from theanchor.

3. A timing mechanism as claimed in claim l including a rotatableshutter winding up shaft, means for rotating said shaft, an extensionintegral with said pivotally supported anchor lever, a cam on saidwinding up shaft engaged by said extension for moving the anchor leverto disengage the said anchor from the gear unit when the said curtainshutter is being wound up.

4. A camera shutter mechanism comprising a first and a second normallyclosed shutter curtain successively released to provide an exposureopening between them, a timing mechanism controlling the time intervalbetween successive releases of said curtains comprising a shaftrotatable with the release of the first curtain, a release disk pinnedto said shaft to rotate therewith, a stop disk freely rotatable aboutsaid shaft and operatively connected with the second curtain, avertically movable and swingably supported stop lever normallydisengaged from said stop disk, a vertically movable rod connected tosaid lever for moving the same into engagement with said stop disk toprevent release of the second curtain simultaneous with release of thefirst curtain, a release lever adapted to be struck by said release diskas the latter rotates with the said shaft for disengaging said stoplever from the stop disk to release the second curtain, an eccentricrotatable button on said stop lever engaging said release lever forsupporting the same in the path of rotation of said release disk, atwo-armed lever pivotally connected to said release lever forpositioning the same in spaced relation to the release diskcorresponding to the length of exposure desired, a middle timing cam, afirst cam nose on said two-armed lever engaging said middle timing cam,an exposure prolonging gear unit, a pivoted arm supporting said unit, agear unit cam, a second cam nose on said pivoted arm, a spring forurging said second cam nose into engagement with said gear unit cam, atoothed segment lever pivoted in the free end of the said pivoted arm, astop finger on said rotatable stop disk, a hook stop nose on saidsegment lever, a second spring for keeping said segment lever inoperative engagement With said gear unit, said second cam nosecontacting said gear unit cam for positioning said segment hook nose inthe path of rotation of said stop disk finger to delay the release otthe second curtain, an anchor pivotally supported on said pivoted arm,an anchor spring normally keeping the anchor in operative engagementwith said gear unit to increase the motion resistance therein, a curtainwind up device, a cam thereon, a three-armed lever for simultaneouslyengaging said anchor and said Wind up device cam to disengage the anchorfrom the gear unit when the shutter is being Wound up, an anchor cam, athird cam nose on said three-armed lever engaging said anchor cam foroperation of said three-armed lever, a timing shaft for integrallysupporting the said three timing cams thereon in superposed relationaxially above the said shaft, a knob on said timing shaft for rotatingthe latter together with the said three cams to move the two-armedlever, the said three-armed lever and the said pivoted arm and themechanisms actuated by the said cams, respectively, to provide desiredtime intervals between releases of the two shutter curtains with orwithout participation of the said delaying means, the anchor, thetoothed segment or the gear unit, respectively, springs for keeping thesaid cam noses in contact with their said respective cams, saidreleasing disk, upon release of the rst curtain, rotating with the saidshaft to strike the releasing lever to release the second curtain, saidreleasing lever being moved tangentially with respect to said timingshaft and in sliding contact with the said eccentric button.

5. A timing mechanism for a camera focal plane shutter in which a rstand a second curtain are successively released and moved to form anexposure opening between them on their travel across the objective eldcomprising means to release the first curtain, a rotatable secondcurtain release disk operatively connected with the first curtain, astop disk operatively connected with the second curtain, a springactuated stop lever engaging said stop disk for said second curtain toprevent release of the second curtain when the irst curtain is released,said stop lever bearing an eccentric knob, a timing cam operativelyconnected with the time setting knob of the camera, a slidably andswingably supported second curtain release member having two oppositecurved sides, one of which sides serves as a stroke side to receive theimpact of said releasing second curtain releasing disk when the latteris rotated upon release of the iirst curtain, the other iof the said twoopposite sides being longitudinally movable in constant contact with thesaid eccentric knob to vary the distance between the said stroke sideand the said releasing disk, thereby determining the time point at whichsaid release disk strikes the said second curtain release member to movesaid stop lever out of engagement with said stop disk to release thesecond curtain, a pivoted lever contacting said timing cam and pivotallyconnected with said second curtain releasing member to operate thelatter and a time setting knob for operating the said timing mechanism.

References Cited in the le of this patent UNITED STATES PATENTS2,122,671 Leitz et al. `luly 5, 1938

